import pygame
from pygame.sprite import Sprite

class Ship(Sprite):
    
    def __init__(self,screen,ai_settings):
        """ Initialize the ship and set its starting position. """
        super().__init__()
        self.screen = screen
        # Load the ship image and get its rect
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()
        
        # Start each new ship at the bottom center of the screen
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom
        
        # Set the speed 
        self.ai_settings = ai_settings
        
        # Movement flag.
        self.moving_right = False
        self.moving_left = False
        self.moving_up = False
        self.moving_down = False
    
    def update(self):
        """ Update the ship's position based on the movement flag. """
        if self.moving_right and \
                self.rect.right < self.screen_rect.right: 
                # Set the range of the ship movement
            self.rect.centerx += self.ai_settings.ship_speed_factor
            
        if self.moving_left and \
                self.rect.left > self.screen_rect.left:
            self.rect.centerx -= self.ai_settings.ship_speed_factor
            
        if self.moving_up and \
                self.rect.top > self.screen_rect.top + self.rect.height:
            self.rect.centery -= self.ai_settings.ship_speed_factor
            
        if self.moving_down and \
                self.rect.bottom < self.screen_rect.bottom:
            self.rect.centery += self.ai_settings.ship_speed_factor
            
    def blitme(self):
        """ Draw the ship at its current location. """
        self.screen.blit(self.image,self.rect)
    
    def center_ship(self):
        """ Center the ship on the bottom of the screen. """
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom
